1. Field of the Invention
This Invention relates to medical imaging and identifying and archiving medical image information relating to a subject. More particularly, the invention relates to a method of automatically extracting information from a text frame image and organizing text information and images in a particular manner which facilitates ease of storage and retrieval.
2. Background Information and Description of the Prior Art
Medical imaging techniques and devices for obtaining high quality medical images have greatly improved in recent years. With the improvement in techniques and quality of images obtained, an increasing amount of imaging is being performed which results in a greater amount of image information to be organized and archived for later reference by radiologists, other medical personnel or other interested parties.
Many medical imaging devices are currently being used in radiology. Although these devices produce images in a variety of forms, the images can all be converted to a form suitable for digital archival and retrieval systems. Digital images can be produced directly by techniques including computed tomography (CT), nuclear magnetic resonance imaging (MRI), ultrasound, digital subtraction angiography and gamma ray imaging In addition, traditional x-ray projection images continue to provide information about many biological systems and these film images can be digitized to a form compatible with digital image management systems. It is envisioned that computer technology which is now being applied to radiology will provide the ability to view, print, and store images developed from any of the aforementioned devices. Additionally, physicians will be interested in retrieving image data about a particular subject generated using all modalities including CT, MRI and x-ray. The basic concepts of various image modalities and image viewing of data generated by such devices are described in U.S. Pat. No. 4,833,625.
Historically, images were stored on films which were filed in various ordering systems. A large percentage of such films are lost, or the films become physically separated from file jackets and it then becomes impossible to identify the subject to whom the film relates. More recently, digital image data is stored in computer archival systems. In conventional MRI and CT systems, many images are generated, each having its own identification number and header information. The header information includes textual information about the patient and about the study being conducted. Typically, groups of these images are arranged to appear together on separate pages, with possibly twelve to twenty images per page. A technician must perform the task of entering the identification information and arranging the images into pages. Physicians typically prefer to review images in a page-by-page format and on film rather than viewing separate original images on screen. As noted hereinbefore, historically the information was archived by saving the films and deleting the original image data. More recently, digital archival systems have been developed which store each of the small images individually.
A medical image filing system was disclosed in U.S. Pat. No. 4,879,665. This involves assigning information to image data and using the information in order to retrieve image data which has been stored. Each separate medical picture or image must have retrieving data associated with it in order to retrieve the image This results in a large number of entries in the directory and time is sacrificed in processing textual information associated with every individual image which is archived.
An image data management system was disclosed in U.S. Pat. No. 4,653,112. U.S. Pat. No. 4,653,112 employs a ring-type architecture data transmission network having nodes comprising data input/output points Node interfaces are provided which allow data to flow between an associated image acquisition device or display console and a host computer. Although a method of utilization of storage capacity for image data is provided, a more efficient means of storing textual information is not disclosed. In addition, U.S. Pat. No. 4,653,112 does not disclose a method of retrieving images from storage based upon such textual information.
Other types of image data acquisition devices and archiving systems have been disclosed. For example, U.S. Pat. No. 4,430,749 discloses a medical imaging apparatus and method for furnishing difference images U.S. Pat. No. 4,437,161 discloses a medical imaging apparatus containing a device for detecting radiation emitted from an object under examination. Both of the these patents relate to magnetic resonance imaging.
Imaging sofware is disclosed in U.S. Pat. No. 4,585,992. A three-dimensional imaging display system was disclosed in U.S. Pat. No. 4,737,921. A method of dual image recording of medical data was disclosed in U.S. Pat. No. 4,665,004 which involves recording a digital representation of an image and saving the raw image data.
As can be seen from the above discussion, methods of image generating and systems for archiving and storing medical images have been known. However, there remains a need for efficient storage of images and textual information in relation to those images. At present there are two classes of digital image archive systems--vendor specific and general purpose. The vendor specific devices are very complex and cannot be easily integrated with equipment from other vendors The general purpose systems suffer from an inability to communicate the textual information associated with an image and hence require a technician to enter the relevant textual information at the beginning of a study as well as prior to archiving image data to be saved. This involves dual entry of the same information. The additional step can lead to typographical and other errors which in many systems cannot be corrected.
In addition, there remains a need for a digital interface communication system which allows immediate retrieval of images from a variety of image acquisition devices. The present trend is for each vendor to provide a proprietary method for the management of image data produced by image acquisition equipment supplied by that vendor. It can be extremely difficult to arrange for systems from different vendors to interact with one another in an efficient manner. Recently, standard protocols have been proposed for image archival and retrieval systems, however, such protocols are extremely expensive and complex and have not been universally adopted by vendors. Although it is extremely desirable, it is not currently practical for image acquisition equipment from multiple vendors to be interconnected into a single image management system in a way suitable for use in radiology departments.
Moreover, there remains a need for a more efficient method of organizing directories which are then used for retrieving image information. At present, the textual data archived by means of digitizing analog signals must be entered a second time as to each set of image data to which it relates. Further, textual information is stored in the computer archiving system for each image generated. Many images are required for one study and this means that there is a great amount of duplication of information stored. As noted hereinbefore, conventional systems involve image-by-image archival systems for which an entry is maintained in the data base for each of the individual small images. The size of such a data base grows very rapidly (about ten million records per year in some institutions) and it becomes progressively more difficult for data to be retrieved.